After I promised myself I would stay away from foam today I bought an old Adire Maelstrom dual 8 Ohm subwoofer for $40. The owner put it back into the original box when he finished using it where it sat for ~15 years he said. It was dusty but surprisingly it cleaned up very well and the coils Ohmed out pretty close. For $40 I figured it was worth playing with.
I plan to use it in a small sealed box as a servo sub with my Erath Electronic Suspension System and a Hypex nc500 amp.
Any suggestions on enclosure size to get it to resonate at 70Hz? I was going to try 1.5 - 2.0 cf since the fs was like 18Hz or something.
And for the title, how does it compare to today's top sub's? I've never tried the nice pro drivers but I do use some of the newer Eminence drivers which, I believe looking at the basket, this is also.
I plan to use it in a small sealed box as a servo sub with my Erath Electronic Suspension System and a Hypex nc500 amp.
Any suggestions on enclosure size to get it to resonate at 70Hz? I was going to try 1.5 - 2.0 cf since the fs was like 18Hz or something.
And for the title, how does it compare to today's top sub's? I've never tried the nice pro drivers but I do use some of the newer Eminence drivers which, I believe looking at the basket, this is also.
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Assuming the Mk. 1
http://web.archive.org/web/20200206...nt/uploads/OldAdireAudiowooferinformation.pdf
Re (Ohms) Z (Ohms) Le (mH) Fs (Hz) Qms Qes Qts Vas (L) Sd (cm^2) Xmax (mm) Pmax (W)
3.4 4 3.5 20 19.10 0.29 0.29 460 1180 13.0 1000
a = [[70-20]*[70+20]]/20^2 = 11.25
Vb = 460/11.25 = ~40.89 L
edit: corrected the HR file
http://web.archive.org/web/20200206...nt/uploads/OldAdireAudiowooferinformation.pdf
Re (Ohms) Z (Ohms) Le (mH) Fs (Hz) Qms Qes Qts Vas (L) Sd (cm^2) Xmax (mm) Pmax (W)
3.4 4 3.5 20 19.10 0.29 0.29 460 1180 13.0 1000
a = [[70-20]*[70+20]]/20^2 = 11.25
Vb = 460/11.25 = ~40.89 L
edit: corrected the HR file
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One of the first diy projects I did in audio was a three-way monitor based on this driver. Not a bad woofer. Especially for that price.
Not as sensitive on top as a pro woofer and power compression would be apparent if fed extended power for long periods of time. i believe it has 3" coils but I might be wrong.
I don't see any issues for typical home use.
Not as sensitive on top as a pro woofer and power compression would be apparent if fed extended power for long periods of time. i believe it has 3" coils but I might be wrong.
I don't see any issues for typical home use.
You're welcome!
Ok, re-break it in and measure its specs and do the math 😉, but being servo drive does it make much difference?
I looked and it "looks" good. I don't know which position it was stored so that is a good sign...
I put it face down and the spider position looks the same.
Oops! Forgot about sag, so with current guesstimate specs it's bumping right up against the 5% limit: 24,849/[20*13^2] = ~4.779 mm
Good to know, thanks! All I know is that they make for an impressive performance.
In this case, best to measure regardless if being off a few Hz makes an audible difference.
I'm listening to a pair of Maelstroms in 3 cf boxes as we speak. I bought them in 2004 and they have had the **** beat out of them and still going strong.
Mind sharing the box construction?
I was thinking two layers of 3/4" mdf for front and rear. Stuffed with polyfil.
I don't really remember but I'm 99% sure they are 1 layer of Baltic Birch plywood all around with the baffle inset about 2". I'm sure two layers would not hurt but they sound fantastic with one. I use a little bit of Linkwitz Transform EQ to get the bottom octave.
Here is a bit of an email from Chris at Adire circa January 2004: As far as box alignments for the Maelstrom go, for a Q of .707, because of it’s low Q design you’re only looking at ~3 cubic feet with 24 oz of polyfill stuffing. I know that you had mentioned that you were looking at doing an LT circuit to get better extension, so you have some flexibility here depending on how much power you can burn up in EQ. Also, if you are ever looking at a vented design for the woofer, 5-6 cubic feet tuned to 30 hz will get you flat down to 30 hz. I’d be glad to forward you on to one of our engineers if you have any more detailed questions about enclosures.
Brett
Here is a bit of an email from Chris at Adire circa January 2004: As far as box alignments for the Maelstrom go, for a Q of .707, because of it’s low Q design you’re only looking at ~3 cubic feet with 24 oz of polyfill stuffing. I know that you had mentioned that you were looking at doing an LT circuit to get better extension, so you have some flexibility here depending on how much power you can burn up in EQ. Also, if you are ever looking at a vented design for the woofer, 5-6 cubic feet tuned to 30 hz will get you flat down to 30 hz. I’d be glad to forward you on to one of our engineers if you have any more detailed questions about enclosures.
Brett
Thanks for that..
My servo controller acts like a LR eq..
My sub in box has to resonate at 70Hz so I was going to build it 20*20*12 with the front baffle inset an inch similar to yours with the driver flush mounted.
My servo controller acts like a LR eq..
My sub in box has to resonate at 70Hz so I was going to build it 20*20*12 with the front baffle inset an inch similar to yours with the driver flush mounted.
Another thing I might mention is we originally ordered that driver for a pro rig that literally rattled 2000 seat theaters with 20 hz bass in a 4-2x18" config. They would blow Meyer 650P's out of the water for tonal quality and true sub bass output so I think they would probably do quite well in a living room.
FWIW, MDF has a ~527,000 psi MOE Vs 0.75" no void marine, Birch, Apple ply's ~1.8 mil psi MOE = 0.75*(1.27/0.5270)^0.33 = ~1.125" MDF thickness to match its stiffness, so a bit stiffer than a 0.75" BB ply construction if all sides are doubled up, though in such acoustically small cabs both ideally need some internal added bracing to tie all six sides together, brace/support the driver.
Cut some wood today.
3/4" mdf
21.5 * 21.5 * 12 inches. Front baffle is inset 1.5 inches and double thickness.
Letting the glue set then I will router all the edges and cut out the hole.
It's very small so I don't think the box will flex much so I went single thickness. If I have to I can put another piece on the back to strengthen that.
3/4" mdf
21.5 * 21.5 * 12 inches. Front baffle is inset 1.5 inches and double thickness.
Letting the glue set then I will router all the edges and cut out the hole.
It's very small so I don't think the box will flex much so I went single thickness. If I have to I can put another piece on the back to strengthen that.
